Agile robots teach each other new tasks in real time. Scanners analyze handwritten notations from any angle. Wireless controls double as standalone monitors. Reliability-Centered Maintenance (RCM) troubleshoots automatically. As the 21st Century begins, the material handling sector draws closer to the paradigm of "clean room" plant operation, where every move is customized and downtime becomes arcane. As illustrated below, technology is making both subtle and profound advances toward that transformation.
ROBOTS GO TO SCHOOL
Robotics is becoming an integral part of the material handling sector, and the use of robots is expected to surge in the next few years. Indeed, the growth of robotics could expand ten-fold in the next decade, according to Mark Handelsman, director of material handling for Fanuc Robotics North America. "The push to use PCs and networks has affected robotics and helped to improve uptime through enhanced diagnostics," Handelsman observes, and the "improvements in user interfaces make the systems easier to operate."
3D vision and force sensors allow Fanuc Robotics'' I-21i robots to randomly position parts in any orientation.
Fanuc Robotics North America has worked to introduce existing technologies in new applications for its customers. "One recent example is our new bag-handling palletizing application," Handelsman notes. "Manufacturers have used robotics for palletizing, but now the concept has been introduced to the bag-handling arena. Existing technologies made this possible."
Adept Technology Vice President of Marketing Joe Campbell points out that robots are "increasingly part of the overall data and control network of manufacturing companies. Technologies like embedded Ethernet and PC connectivity are allowing robots to be integrated into MRP [Material Requirements Planning] systems and become very active in overall flexible automation and handling operations."
More than 100 government, university, and industry laboratories focus on robotics research. These facilities are exploring electromechanical, computing, and mathematical areas that could lead to an advanced generation of robots.
Columbia University''s robotics group, for example, has developed a set of algorithms that performs precise alignment and positioning without the need for calibration. Columbia is also investigating autonomous precision manipulation for robotic hands. Its robotics lab has been studying the use of tactile information to recover 3D data. The Institute for Robotics and Intelligent Systems (IRIS) at the University of Southern California continues to study biologically based behavior, applying this research to multirobot and humanoid robot control. IRIS states that its "methods for learning in multirobot systems are aimed at addressing the problems of nonstationary conditions...the role of communications, task-sharing...and imitation."
At Brown University, the National Virtual Laboratory is experimenting with the control of robots across a computer network. The University of Texas at Austin is developing advanced obstacle avoidance technology. Carnegie-Mellon''s Robotics Institute pursues projects in visualization and interfaces, intelligent coordination and logistics, intelligent sensors, artificial intelligence, field robotics, medical and surgical robotics, space robotics, and computer vision. Carnegie-Mellon also hosts the National Robotics Engineering Consortium, which is "dedicated to the development of products incorporating advanced mobile robotics technologies" and is "currently developing robotic vehicles for the mining, earthmoving, agricultural, and industrial material handling industries."
The Stanford Robotics Laboratory aims to make robots more autonomous through "vision and image understanding... planning...reasoning, machine learning, geometrical modeling, and navigation." The University of Minnesota, The University of Michigan, Rice, Cornell, and other institutions all commit resources to developing new robotics technologies, research that will be discussed in future issues of IEN and ienonline.com.
Breakthroughs in off-line programming are not far off. "Technologies have come together as of late to improve the accuracy of robots and modeling packages," Fanuc''s Handelsman believes. "Cost-effective PC-based programming tools will take off."
This Fanuc top loader can perform several intricate tasks in a single cycle.
Fanuc recently introduced the I-21i robot, which allows for advanced assembly operations with the use of 3D vision and force sensors. The robot is a six-axis intelligent robot that can perform skilled operations because of its vision and force sensing capabilities. A major manufacturer is currently working with Fanuc to develop process solutions using this next-generation system. The robot''s 3D visual sensor can locate randomly positioned parts in any orientation.
Fanuc''s M-16iT is part of a new family of overhead rail-mounted robots, now being used in metalworking and other applications. "Our customers wanted a robot that is fast and flexible and capable of performing a variety of intricate tasks in a single cycle," says Peter Fitzgerald, general manager of Fanuc Robotics Canada Ltd. The modular-built, electro-driven robots are designed for load/unload applications in the machine tool and plastics industries and are available in three models, M-6iT, M-16iT, and M-16iLT. The models offer a variety of reach and payload capabilities.
"The top loader [M-16iT] will free up some floor space in the cells since the only space required for the robot is for two support legs," says Beth Nelson, manufacturing engineer at Melroe Co., manufacturer of the Bobcat Skidsteer Loader and one of the first buyers of the product. "We''re really tight on floor space in this cell, so it was great timing to have this product available for purchase." Melroe will be using the M-16iT "in cells with a two lathe application where we used to have two robots," adds Nelson. "Now we can get by with one robot."
The robots'' six axes of motion (one linear and five rotary) result in a "mobile" robot capable of servicing multiple machines, stations, or operations. In addition, this dexterity provides the ability to reorient parts between operations as well as service both vertical and horizontal machines.
The rail mount allows top, front, or side entry into the machine tool, and also allows the robot to reach back behind itself to provide a three-dimensional work envelope, as opposed to the two-dimensional work envelope offered by a traditional linear gantry. The overhead mount allows a full range of motion for secondary operations such as trimming, washing, deburring, palletizing, labeling, or packing. It also reduces floor space and ceiling height requirements compared to gantry robots and keeps the front of the machine tool clear for tool change and maintenance.
Safety Standards
The material handling industry is increasingly concerned with safety issues, and has put considerable time and resources into the safety design aspects of conveying and handling systems and associated automated processes.
Banner Engineering Safety Products Marketing Manager Victor S. Caneff observes: "From the integration of safety light curtains and related muting circuitry at the entry and exit points of palletizers to the implementation of highly reliable e-stop and controlled stop functions on robots, system designs continue to evolve. As the industry moves toward higher speeds and greater levels of automation, the risk associated with the equipment can increase. Increased risk of severe injuries will require greater attention to integrating additional safeguards and to the level of performance from the safety system." Banner''s ES-TN-1H5 E-stop safety module, which includes delayed outputs, provides a "controlled stop" on robots and other equipment.
The U.S. robotics industry established new safety standards in the summer of 1999. The Robotics Industry Association (RIA) has led the effort to establish new ANSI standards for robot installations and operation in North America. "These standards were a substantial rewrite of existing safety standards and were adopted from the [European] CE standards," according to Fanuc''s Handelsman.
Adept Technology''s Joe Campbell notes that CE standards are well established and provide explicit guidelines for manufacturers and users of automation technology, allowing European industry to manage risk. "Responsible manufacturers have redesigned their products to meet the new requirements, and are embracing the regulations," says Campbell. CE standards are part of EU law.
Streamlining Material Handling
As a key part of its business activities, Unifi Inc. has historically purchased a chemical-based product called multifilament partially oriented yarn (POY) from chemical and fiber companies. POY is the raw fiber used to produce textured polyester and textured nylon yarn. Unifi''s texturing processes give the POY bulk, crimp, strength, and consistent dyeability. The yarn is then sent directly to Unifi''s fabric-producing customers, or it undergoes further internal processing such as dyeing, covering, beaming, or twisting before shipping. In order to balance its requirements for POY Unifi management decided to integrate domestic production of some of its POY requirements.
By reengineering the POY production process, Unifi created a fully automated, state-of-the-art production line and materials handling system. Designed to produce up to 25% of Unifi''s domestic POY requirements, the Yadkinville plant was set up and implemented in less than 14 months. Unifi''s automation and facilities design engineers were able to combine state-of-the-art spinning equipment technologies with innovative material handling methods.
As Max Cranfill, Unifi Corporate Director of Automation, notes: "Effective automation becomes a requirement when you have over 3.5 million pounds per week of product coming at you, which must be handled in integrated groups, each consisting of six 45-pound packages." Although existing POY production methods make significant use of automation techniques, Unifi''s design team quickly identified a number of key areas in which efficiency could be improved and the risk of production downtime could be reduced.
Key design goals were established for the new automated facility, which included: (1) reducing handling of POY packages; (2) maximizing efficiency by keeping the spinning machines as fully utilized as possible; and (3) minimizing downtime by eliminating single-point failure risks with critical operations and by building in flexible redundancy wherever appropriate.
Unifi selected Greenville, SC-based Advanced Automation as their primary integrator and design partner for implementing the Yadkinville POY production facility. Together, the Unifi team and Advanced Automation conducted a detailed review of the current POY production techniques to identify areas for potential improvement.
During their visits to existing POY facilities, the design team observed a consistent tendency to delay packing of the POY product until it was "proven" to be good product. The POY product was initially off-loaded from the spinning machines and then relocated to a separate storage area, usually an overhead carousel, until test data were available for that production run. Then it was moved from the storage area into the subsequent process for labeling and packing. This philosophy essentially caused all of the POY to be handled many times prior to final packing, even though there was nothing wrong with the majority of the product units.
Under the redesigned system, everything is packed, assuming good production results, with exceptions sub-coded based on test data. By incorporating detailed product tracking techniques, the Unifi process can efficiently retrieve any nonconforming product from the downstream operations, without sacrificing the overall efficiency of the entire production line. As a result, the Unifi system can reduce handling to a maximum of four operations, as compared to 8-12 for existing systems.
In addition to the inefficiencies associated with excessive handling, there is also the inherent risk of damage and/or labeling/processing errors associated with each handling operation. The raw POY packages are extremely susceptible to contamination and/or damage. Each additional handling operation increases the risk of turning good product into waste and scrap. In addition, while every raw POY package looks exactly the same to the human eye, each has unique chemical and physical characteristics, which determine its dyeability properties. This means that the accurate labeling and processing of data associated with every package is paramount to avoiding the mismatching of products, which can cost even more in waste and scrap when discovered after subsequent texturing and dyeing operations or fabric forming operations.
The heart of a traditional POY plant is a material handling device known as a "doffer". The doffer is usually a multiaxis Cartesian robotics system mounted on fixed rail, which allows it to traverse all of the spinning machines on a single aisle of the production line. The doffer''s primary functions are to remove completed POY packages from the winder mandrills on each spinning machine, to rotate/reorient the POY packages; and then to traverse the floor and deposit the POY in horizontal arrays on overhead, rail-mounted carriers for subsequent processing and packing. The doffer was typically also responsible for distributing empty spools to the lower spindles of the spinning machines, to be used for the next spinning operation.
Because a single doffer is dedicated to service only the spinning machines in a single production aisle, the traditional technique presents significant risks of overall inefficiency and downtime. Most significantly, the doffer represents a classic possibility of single-point failure. If the doffer experiences downtime, the impact is felt throughout the entire aisle of spinning machines, because no finished spindles can be retrieved and overall production may come to a halt.
According to Unifi''s Cranfill, "The impact of a single-point failure and widespread production floor downtime becomes even more critical when you consider that all of the spinning machines are fed with molten polymer, which must be kept constantly moving in the supply lines. The consequences of even a short floor-wide production stoppage could lead to significant delays required to clean and restart the clogged lines."
This single dedicated doffer approach injects ongoing inefficiency because the production utilization of every spinning machine must be adjusted to meet the doffer''s fixed scheduling. This can force the production scheduler to constantly reprogram intricate doffing schedules and/or to (sub-optimally) off-load partially complete POY spindles to avoid disrupting the overall sequence of doff times for the entire line.
Advanced Automation and the Unifi team designed an entirely new system using automatic guided vehicles (AGVs) as a flexible and more efficient replacement for a single, fixed-rail doffer. The use of several AGVs that can service any site spinning machine on the production floor addresses the overall goals of reducing downtime risk while simultaneously improving system efficiency. Single-point-failure risk is eliminated because, if any particular AGV experiences downtime, the other AGVs can quickly be rerouted to maintain service to all of the spinning machines. Efficiency and scheduling flexibility are both improved because the individual spinning machines no longer must conform rigidly to the doffer''s fixed sequence of movements. Every spinning machine can run to its maximum utilization rather than being sub-optimally driven by dictates of the overall doffing schedule.
The Unifi system deploys eight AGVs to service 26 separate 12-winder spinning machines, for a total production floor capacity of 312 winders. The AGVs, provided by Munck-Autech of Newport News, VA, pick up completed POY packages from the spinning machines in blocks of three consecutive spindles at a time. The AGVs deliver the three-spindle blocks to one of three "singulating robots" provided by Adept Technology. Each Adept robotic singulator is designed to receive the POY from the AGVs and place them into horizontal arrays on the conveyor-transported pallets (pucks) for subsequent processing. The system design utilized three singulators, thereby always allowing for two stations to simultaneously service the production floor, even if the third machine was taken down for maintenance, programming, or upgrade.
According to Ken Strittmatter, applications engineer and project manager of Advanced Automation, "Adept was chosen to provide robotics for the three singulator stations primarily because of the need for high reliability as well as the requirement for designing and deploying customized functionality on a very tight time schedule. A custom end-effector was designed to mate with the AGV mandrills, whose form factors were dictated by the mandrill designs used on the spinning machinery. In addition, the singulator robot needed to incorporate an auxiliary axis to push the POY packages on to the puck spindles. Overall payload and throughput was also a key for the singulating stations, since the two stations had to consistently service all eight AGVs and 312 production spindles without causing delays or back-ups on the production floor."
After the singulating stations have finished filling each conveyorized puck to its prescribed level, the conveyor system moves it through the labeling, curing, and inspection operations; ultimately delivering the packages to two gantry robots supplied by C & D Robotics of Beaumont, TX, that handle the packing and shipping operations. The gantry robots are also fitted with Adept controllers in order to provide a common controller/programming environment throughout the plant.
One of the primary keys to quality assurance in the textile industry is maintaining tight control over the integrity of the raw yarn from the time it is produced, through all subsequent handling and shipping, to ensure consistent results from the texturing and dyeing processes. The new Unifi system minimizes the risk of errors by eliminating all extraneous handling steps. In addition, Unifi has instituted disciplined process for maintaining package integrity during all materials handling steps and for tracking the packages using RF identification tags.
From the time the raw POY product is first removed, it is kept in same six- package groupings as it was created on the winding machine''s spindles. Throughout the movements from the AGV to the singulator to the conveyorized puck, the six-package grouping is maintained. The conveyorized puck with POY incorporates a RF ID, provided by ISC OMROM of Scituate, MA, which contains all relevant data on the POY. The RF ID tag stays physically resident with the POY package and accumulates additional data throughout process. As the package passes through the test queues, inspection stations, labeling stations, and final packing/shipping, the RF tag automatically communicates with the programmable logic controllers (PLCs), provided by Omron Electronics, of each subsequent station to ensure correct processing and to record appropriate data. At any point that the system needs to retrieve, reroute, or alter the process for a particular package, the automated data tracking supplied by Camstar Systems allow for timely and efficient adjustments.
Rethinking A System
Visteon Automotive Systems, an enterprise of Ford Motor Company, recently initiated a new manufacturing system in order to accommodate the latest body electronics for Ford''s Lincoln-Mercury, Jaguar, and Windstar models. According to John Colarusso, manufacturing engineer at Visteon, the company had some of its first new workcells on the floor--and fully operational--within three days of delivery, saving more than $1 million in the process.
"Ford specified a tight time frame for the project--12 months for completion of the first product build and 18 months to production volume ramp-up," says Colarusso. The project involved designing two new assembly lines to build the five-module families responsible for controlling security, lighting, convenience group, power steering, turn signals, and other electronic functions.
The designs for the assembly lines needed to be scaleable and flexible to accommodate future changes in the modules. Visteon accomplished this by decreasing its original system count from 15 to 11, and by making sure that it got as much functionality from each workcell as possible. This helped save floor space and increase cycle time, with reduced handling along the line. "Each second really counts in our industry," Colarusso emphasizes. "The fewer workcells you have, the faster the product goes through the line, and the more productive your facility is. We needed each system to do as much as possible, and we wanted to leave room for expansion."
Adept Technology reconfigured its robots for Visteon. A new "brain" costs about half as much as a new robot.
One of the most important elements of the redesign project was the use of reconfigured equipment. Visteon believes that equipment should be purchased for the long term--not just for the length of a particular project. The company has been relying on Adept Technology robots for a decade and wanted to continue working with this equipment, rather than buy new robots. "Reconfiguring a robot can be done for about half the cost of buying a new one," states Adept''s Campbell. "Give a robot a new ''brain'' to accommodate each new project, and you end up with a capital investment that continues to pay off for years. A robot can be reused and reconfigured many times. The life span varies depending on the application, but we''re seeing longevity of around 90,000 hours."
YOU ARE WHAT YOU READ
Holographic scanning has grown more popular in material handling applications in recent years. This technology excels in the large scan areas prevalent in packaging, warehouse distribution, and material handling. A holographic scanner is basically a round disc treated in a photographic emulsion. It contains multiple lenses, which can focus at different distances and can read bar codes from any height and angle. Non-holographic technology is limited to reading a single line or X pattern.
Holographic technology is not applicable to handheld scanning, or supermarket and retail store scanning, because there is not enough depth-of-field in those end use markets.
"Omnidirectional scanning applications continue to increase," says Frank Lodge, product manager for industrial scanning at Metrologic Instruments, the leading force in holographic technology. "Some manufacturers respond with omnidirectional scanners such as Metrologic''s new Penta scanner, which simultaneously scans in five directions," he adds, while "other manufacturers are responding with clusters of linear scanners."
Material handling managers now demand ever greater levels of sophistication from scanning technology. Notes Lodge: "An increasing number of users want not only to identify codes on packages, but to associate the code with the package for sorting and tracking purposes. Faster microprocessors have enabled Metrologic to calculate a code''s 3D spatial geometry in real-time making sorting and tracking ever more accurate."
Many companies also "choose bar codes as pointers to computer data records," Lodge says. "These users employ short 8-, 10-, and 12-digit identifiers that are readable at high speeds. Others are choosing two-dimensional bar codes with more data content, which are more demanding and expensive to read."
The HoloTunnel, Metrologic''s most comprehensive scanning system to date, scans bar codes on up to six sides of parcels moving down a fast conveyor, and includes dimensioning, weighing, and labeling capabilities. A significant component of Metrologic''s holographic technology is the Holodisc, which contains up to 24 holographic elements that focus a laser beam, sweep it across the bar code, and then receive the reflected light back from the bar code. As the Holodisc turns, it focuses several laser beams into multiple focal planes to create thousands of scan lines per second, resulting in a very large, dense scan field.
What''s Next?
Holographic technology promises to bring several advances to the material handling front in the next few years. CD-sized holodisks will "lead to less expensive holographic scanners and innovative solutions in markets now served by conventional scanners," according to Lodge. He also predicts that a single scanner will read "multiple sides of packages, both front and rear." Local and remote internal diagnostics should improve scanner uptime and "remind users when routine maintenance will improve performance."
Metrologic is devoting a lot of research dollars to developing edge/corner detection technologies. The human eye has very sophisticated edge detection ability. It identifies color boundaries precisely, and fills in the colors between on an averaging basis. "We are using scanning lasers to detect height, width, and length," explains Lodge, "then trying to track virtual boxes through space." This technology could allow users to read packages in new ways--not just transmitting bar codes, but submitting data to a handwritten character recognition system, for example.
Stanford''s Computer Science Dept. has conducted research in this area as well, developing models that address problems in corner detection. Other research efforts may eventually end up in material handling applications. The Integrated Small Precision Optics Manufacturing Technology Consortium (ISPOMT) wants to create sophisticated retinal scanning display systems from advanced technological component technologies. The Rockwell Science Center leads the consortium, which is partly funded by the U.S. Office of Naval Research as a Dual Use Application Program (DUAP). Last June Mircovision, a leading developer of Virtual Retinal Displays (VRD) technology, joined the consortium, and plans to "provide crucial system integration and commercialization capabilities," according to the consortium. Other members of the consortium include the University of Washington/Human Interface Technology Laboratory, Polaroid Corp., Ford Motor Co., and New Interconnection and Packaging Technologies Inc.
The technology has the potential to achieve breakthrough advances in cockpit situation awareness, manufacturing plan design and operation, medical diagnostics, and surgery, the consortium states. ISPOMT members provide display and human computer interface concepts, as well as precision optical components including micro-optics, rugate filters, microelectromechanical systems (MEMS), and diode lasers.
Metrologic''s Lodge believes that retinal scanning has more potential applications in the pick-and-place side of material handling than in bar code reading.
Finally, research in human eye recognition scanning technology is progressing. While this area presently centers on possible ID systems for automatic teller machines, material handling applications should not be ruled out further down the line.
Holographic Scanning Goes To Airports
In 1999 Metrologic formed a joint venture with the 2nd Institute for Research and Development of the Civil Aviation Administration of China (CAAC) to develop and market baggage handling and sorting systems for use at certain Chinese commercial airports.
Under the agreement, Metrologic is working with the CAAC to develop specialized automated bar code scanning systems for baggage identification and handling. The company will combine its HoloTunnel scanning technology and other equipment with conveyor and sorting systems provided by the CAAC. Many of China''s 225 civil airports in China are expected to upgrade their baggage handling facilities in coming years. The company has added scanners configured to read bar codes in the International Air Traffic Association format to its current product line.
Metrologic will provide technical support, service, and product integration for this venture from its new facility in Suzhou, China. The company''s Metro (Suzhou) Technologies Co. Ltd opened in October 1999. The new facility is dedicated to research, development, and the manufacturing of laser scanners. It is located in the Singapore-Suzhou Industrial Park, a joint venture between the governments of Singapore and China.
Tracking Trailers
DaimlerChrysler significantly increased the number of Metrologic HoloTrak IS8500 omnidirectional bar code scanners installed at its assembly plant entrance and exit gates last year.
Since first installed at DaimlerChrysler in fall of 1997, HoloTrak scanners have consistently read bar coded identification numbers and Standard Carrier Alpha Code (S.C.A.C.) bar codes on tractor trailers moving through its automotive assembly plants. DaimlerChrysler''s PC-based host system then directs each trailer to the correct loading dock. This automatic data entry system eliminates the need for manual data entry and reduces the amount of time guard station employees spend on each tractor trailer.
The automaker has "worked closely with the Automotive Industry Action Group (AIAG) to create a single, high-quality bar code label which will be used by all carriers throughout North America for trailer identification," according to DaimlerChrysler senior analyst Tom Northrop. This standard label will work with HoloTrak to ensure "data accuracy, yard data integrity, and speed in processing arriving and departing trailers," Northrop adds.
Even in the absence of a standard label, the omnidirectional, dense scan pattern projected by Metrologic''s HoloTrak scanners effectively reads bar codes of many sizes and densities, even labels positioned at an angle. Encased in a specially designed heated/ventilated outdoor enclosure for protection against the environment, these scanners read bar codes reliably even in bright sun, rain, clouds, or snow. The HoloTrak IS8500 projects an 80-line omnidirectional scan pattern capable of scanning trucks at various distances.
WRINGING MORE OUT OF WIRELESS
Remote controls reached widespread commercial use in the late 1950s. While most industries mature within 25 years, technological innovations and end user demands have kept this sector vibrant. Material handling applications have burgeoned as industry replaces equipment and machinery.
"Today the use of remote control systems on lifting equipment such as cranes and hoists is becoming increasingly popular within a wide range of industries," notes Nora M. Songer, marketing coordinator at Cattron Inc., a leading developer and manufacturer of remote control systems and RF data links. "Railroads, dockyards, agriculture, paper mills, mining, and foundries have seen the greatest growth in the use of this technology." Songer adds. The shift to wireless controls has resulted in improved safety, increased productivity, and lower operating costs.
"It is likely that there will be a move towards totally automated systems," Songer believes, "where remote controls are used to supplement other forms of control such as global positioning systems (GPS), programmable logic controllers (PLCs), and inertia guidance." PLC/remote controls could be used "as standalone monitors," she adds.
A Retrofit Success
Cattron views the retrofit market as a major potential user of wireless controls, as companies phase out pendant or cab control technology. And as the "number of tower cranes increases both in the U.S. and abroad," says Songer, the construction industry "looks to be a growth area for remote control as well."
Cattron portable remote controls give Nova Steel crane operators tighter walk-through and increased rotation.
One example of the retrofit business is Empire Comfort Systems'' decision to update its crane system. The company, which designs and manufactures gas-fired zone heaters, installed Cattron portable remote controls after an evaluation by Handling Systems Inc. The facility''s aging crane controls and conductor tracks required frequent maintenance.
"Empire was using a bridge crane equipped with a motorized interlocking latch so the hoist [could] run off the bridge onto a monorail spur," a Handling Systems expert recalls. "Farther down the line, a second motorized latch was used for travel outside onto a rotating job crane used to unload the steel coils from trailers. One four-button pendant controlled the hoist and trolley movement. The second four-button pendant controlled the bridge and motorized latch....The operator, with a pendant in each hand to operate the hoist, bridge, and trolley, didn''t have a hand free. So he used his knee or body to guide the coil onto the de-reeler."
Empire decided to replace the hoist and other components, and added a Cattron radio control system. A shift to wireless controls "increases the safety of the operator by giving him total control of the travel speed by varying the finger pressure applied to the radio transmitter keypad," notes the Handling Systems source. "It also reduces the impact to the crane components by providing smoother starts and stops and...reducing wear on brake and motors."
Computers, Too
Computer assembler Foxteq was another convert to advanced remote control technology. Foxteq had been operating a 15-ton and a 100-ton crane with a low frequency control system. The cranes are used both on the assembling where computer castings are manufactured, and in the loading bay for loading and unloading of computer parts.
Operators discovered that their cranes were carrying out unplanned movements because of interference with the control system''s radio frequency. Carlin Systems recommended Cattron''s IT series as a solution. The IT-B pushbutton portable remote controller sends a highly secure serial message, preventing unwanted operations. Its multifrequency synthesized radio system allows the operator to change channels easily and automatically tune the receiver to appropriate channels.
Smoothing Speed
Overhead crane users have increasingly turned to variable frequency drives (VFD) for motor speed controls from magnetic contactor panels or static stepless controls, according to Telemotive Industrial Controls. VFDs use solid-state electronics, rather than a series of contacts, and provide proportional speed control. These drives can "potentially provide a smooth speed range," says Telemotive, in which the "speed of the crane motion is directly proportional to the amount of pressure applied to the control switch." Given better control of acceleration, crane operators can "decrease the amount of load swing and improve positioning."
Telemotive''s SCS system provides the interface between the operator control and VFD. One set of relays controls the speed of each crane motion. The crane operator uses a wireless pendant style or belly box transmitter; there the pressure applied to a button or lever is converted to a DC output voltage for the VFD.
Keeping An Eye On Lift Trucks
More companies are also looking to wireless controls as a way to monitor their material handling vehicles. Ford and Hallmark, for example, track their material handling fleets with I.D. Systems Inc.''s RF-based technology. The technology can also monitor and control the movement of objects, equipment, and packages. Federal Express, Avis, QVC Inc., the U.S. Postal Service, and Dana Commercial Credit Corp. all use I.D. Systems'' controls.
On the safety and security side, the wireless system controls access to vehicles, requires operators to enter electronic pre- and post-trip OSHA checklists, and generates automated, paperless records of compliance with OSHA standards and rules. The system increases fleet efficiency by automatically recording vehicle operation by in-motion and engine-on use; visually monitoring location; communicating work instructions to operators through two-way text paging; and tracking frequency of lift activity. As for maintenance management, the wireless monitoring design sets up preventative maintenance (PM) schedules; automatically generates work orders based on these schedules; and tracks and analyzes labor and parts costs (and usage) by vehicle and for the entire fleet.
Ford uses I.D. Systems'' automated vehicle tracking system to monitor the forklifts throughout its Michigan truck plant. Hallmark, which already manages its material handling fleet with the patented system, recently asked I.D. Systems to develop several prototypes of a new battery-tracking module that will monitor the battery charge on industrial vehicles.
RCM OPTIONS
Reliability Centered Maintenance is considered a key tool for reducing downtime and optimizing all plant operations, including material handling. A plethora of consulting firms provide RCM solutions to industry, although few focus on any one specific sector.
HK Systems, a leader in the automated material handling field, last year introduced Enterprise/EMS, a maintenance software package for any automated environment.
Built with modular, configurable drivers, Enterprise/EMS controls nearly any combination of equipment makes and models. A menu of configuration tools lets companies design the application to specific equipment and business rules. Users can alter the system as requirements change. The software is built upon the Enterprise/Component Management Architecture (CMA)--a distributed framework that utilizes an object oriented approach to allow easy configuration and extension. Enterprise/CMA is also a CORBA-based framework, implemented in JAVA, which supports operation over multiple servers and allows redundant equipment configurations to be managed from a single console. Enterprise/EMS provides the controls sorting equipment, carton and unit load conveyors, monorail, tote stackers, mini-load and unit load cranes, automated guided vehicles, and palletizers. The system includes inventory management and provides for interfaces to other nodes of an enterprise control architecture.
JMS Software offers RCM WorkSaver, which runs under Windows 95, 98 or NT. The program follows a classic RCM systems analysis process and can be used for abbreviated studies. JMS recommends that systems that fall "into the 80/20 rule (80% of problems from 20% of the systems) [use] the classical analysis." Even then, the program is designed to save time. Each screen will "automatically sort data by component ID numbers, functional failure, failure modes.... This information is automatically transferred from step to step," according to JMS.
Aladon Ltd.''s RCM 2 process sets "primary performance parameters such as output, throughput, speed, range, and carrying capacity," the company states. "Where relevant, the RCM 2 process also defines what users want in terms of risk (safety and environmental integrity), quality (precision, accuracy, consistency and stability), control, comfort, containment, economy, customer service, and so on. The process then identifies "ways in which the system can fail to live up to these expectations (failed states), followed by a FMEA (failure modes and effects analysis), to identify all the events which are reasonably likely to cause each failed state."
Ultimately, RCM 2 sets a management policy "for dealing with each failure mode in light of its consequences and technical characteristics." These problem areas then may be addressed by various solutions, including predictive maintenance, preventive maintenance, and operational or design changes.
American Management Systems Inc. (AMS) suggests considering the RCM ''Backfit'' process, which "validates existing maintenance requirements using basic maintenance principles and can be developed at a fraction of the time and cost" of classic RCM analysis. AMS outlines the ''Backfit'' process as follows:
Step 1: Determine the specific failure mode the preventive maintenance task is designed to prevent. This would normally be a dominant failure mode identified in the original Failure Modes and Effects Analysis (FMEA). The task description should allow the analyst to determine what condition the task is designed to prevent.
Step 2: Determine whether this specific failure mode is likely to occur in service as a result of age degradation. Unlikely failures do not require preventive maintenance tasks.
Step 3: Classify the task as a time-directed, condition-directed, failure-finding, servicing, or lubrication task. This is important because there are different rules for task applicability that are linked to specific types of tasks.
Step 4: Apply the rules for task applicability for the type of task specified. These rules are based on failure characteristics. If the applicability rules established for that type of task are not met, the task is not applicable. If they are satisfied, proceed to Step 5.
Step 5: Apply the rules for task effectiveness. These rules are based on failure consequences. If the effectiveness rules established for that type of task are not met, the task is not effective. If they are satisfied, proceed to Step 6.
Step 6: Examine whether further improvement can be made to the task as it is now specified. Even though the task may currently satisfy the rules for effectiveness, further improvement may still be possible.
The RCM ''Backfit'' approach "does not waste resources by recreating the original basis for PMS [Preventive Maintenance System] tasks; it takes the tasks as they are and determines whether they still make sense," AMS observes.
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